1. Field of the Disclosure
This disclosure relates generally to drilling apparatus that includes a steering device for drilling deviated wellbores.
2. Background Art
Oil wells (also referred to as “wellbores” or “boreholes”) are drilled with a drill string that includes a tubular member having a drilling assembly (also referred to as the “bottomhole assembly” or “BHA”) at an end of the tubular member. The BHA typically includes devices and sensors that provide information relating to a variety of parameters relating to (i) drilling operations (“drilling parameters”); (ii) behavior of the BHA (“BHA parameters”); and (iii) parameters relating to the formation surrounding the wellbore (“formation parameters”). A drill bit attached to the bottom end of the BHA is rotated by rotating the drill string and/or by a drilling motor (also referred to as a “mud motor”) in the BHA to disintegrate the rock formation to drill the wellbore. A large number of wellbores are drilled along contoured trajectories. For example, a single wellbore may include one or more vertical sections, straight sections at an angle from the vertical, curved sections and horizontal sections through differing types of rock formations. To drill non-vertical sections of the borehole, a steering unit is often employed in the BHA. One type of a steering unit includes a number of force application members on a non-rotating sleeve. The force application members apply force on the wellbore wall to direct the drill bit along a desired path. It is desirable to provide such a a steering unit as close to the bit as practical to alter the drilling direction so that highly curved wellbore sections may be built with a relatively short curvature (or radius).
The present disclosure provides a BHA that may be utilized to drill short radius wellbores and further includes a variety of sensors that provide measurements for determining downhole parameters of interest.